Apparatus for separating materials



W. W. STEVENSON. JR APPARATUS .FOR SEPARATING MATERIALS April 17, 1934.

4 Sheets-Sheet 2 W. W. STEVENSON, JR

APPARATUS FOR SEPARATING MATERIALS Filed DGO. 22. 1931 pril 17, 1934.

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APPARATUS FOR SEPARATING MATERIALS Filed Deo. 22, 1931 4 Sheets-Sheet 3Oo o o ooo o o o oOo o o o o 88g 00.000000.

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APPARATUS FOR SEPARAI-ING MATERIALS Filed Deo. 22, 1931 4 Sheets-Sheet 4mi my,

1' wey Patented Apr. 17, 1934 UNITED srArss 1,955,032 APPARATUS vFonsEPARA'rING MATERIALS Winfield W. Stevenson, Jr., Steinman, Va.,assigner to Cumberland Coal Cleaning Corporation, Bristol, Va., acorporation of Virginia Application December 22 1931, Serial No. 582,598

4 Claims.

My invention relates to apparatus for separating from a mixture ofmaterials previously graded as to size, pieces of material of dierentcharacters, and more particularly for separating such materials, ascoal, from impurities occurring therewith as slate, bone, shale or thelike.

In accordance With my invention, which for brevity will be describedmore particularly with respect to the separation of slate from coal, themixture, previously graded as to size, as by a screen, or the like, ispassed over a vibratory surface, preferably, downwardly inclined, havingopenings with which are associated more steeply inclined secondarysurfaces defining elongated slots. The pieces of coal and slate being ofdifferent general shapes, ofudiiferent weights or specie gravities, andof different co-eflicients of friction with respect to the vibratorysurface, the pieces of coal pass over the openings continuing along thevibratory surface to a suitable receptacle or destination, While thepieces of slate upon falling on the secondary surfaces slide through theslots to another suitable receptacle or destination. Y 1 Moreparticularly in accordance with my invention, the secondary Isurfaceshave imparted thereto, preferably at a rate corresponding with thevibratory movements of the primary surface, movements substantially toclose the `openings in the primary surface, more particularly for thepurpose of freeing the openings from slate or material otherwise tendingto accumulate therein to the detriment of continued efliciency of cleaing or slate separation.

Further in accordance with my invention, instead of separating the coaland slate mixture in batches of different size grades, and then cleaningthe batches of slate, the coal and slate mixture passing through agrading screen moves directly to a vibratory cleaning surface of thecharacter aforesaid, while the coal and slate mixture passing throughanother or other grading screens move to corresponding cleaning surfacesfor sep aration of slate.

More particularly in one form of my gradin and cleaning system, amixture of coal and slate of many sizes flows over a series of gradingscreens, the screen openings being progressively larger in the directionof flow successively to remove the larger and larger sizesof coal andslate from the mixture, and the graded coal and slatemixture passingthrough each screen falls on a cleaning plate, preferably vibrated inunison therewith, the cleaned, graded coal passing from each plate to asuitable destination, and the graded slate passing through each cleaningplate to a suitable point.

In another form of my grading and cleaning Systemthe main gradingscreens are disposed one above the other, the bottom screen having thesmallest openings and the screens above each having larger openings thanthe screen below, and the coal and slate not passed through each screenmoves to a'cleaning plate of the character described. The larger coal oneach plate passes to a suitable destination While the slate and anysmaller coal which did not pass through the main screen drops on anauxiliary screenV which rejects the slate and removes the coal bypermitting it to fall through onto the cleaning plate below whichreceives the smaller size coal and slate mixture from the lower mainscreen. nThis modification, vin particular, results in coal having avery low percentage of slate with negligible lossof coal.

My invention resides in apparatus of the character hereinafter describedand claimed.

This application is a continuation in part of my application Serial No.506,887, filed January 6, 1931. y

Fig. 1 is a simplied side elevational view, partly in vertical section,of a separating or cleaning system embodying my invention.

Fig. 2 is a sectionall side elevational View on larger scale of aportion of the apparatus shown in Fig. 1.

Fig. 3 is a cross sectional View, taken on the line 3-3 of Fig. 2.

Fig. 4 is an enlarged sectional view, partly in elevation, taken on theline 1 -4 of Fig. 3.

Fig. 5 is a fragmentary top plan view of structure shownin Figs. 1, 2,etc.

Fig. 6 is a fragmentary plan view illustrating a modification.

Fig. '7 is avertical sectional View, parts in elevation, illustrating amodication of the structure of Fig. 2.

Fig. S is a sectional view, partly in elevation, looking from the lefttoward the right in Fig. '7.

Fig. 9 is a simplified side elevational View, principally in section, ofa combined'grading and cleaning system.

Fig. l0 is a side elevational view in section of another grading andcleaning system.

Fig. 1'1 is a plan View of Fig. 10.

Fig. 12 is a side elevational view, in section, of a grading andcleaning system with provisions for recovering coal from slate.

Fig. 13 is a sectional view, in front elevation, taken on line 13-13 ofFig. 12.

Fig. 14 is a plan view of Fig, 12 with parts broken away better toillustrate the construction.

Referring to Figs. 1 to 5 inclusive, 1 is a screen, plate or table, ofsheet metal or the like, whose upper surface is the primary surface overwhich the mixture of materials as coal and slate pass from upper rightto the lower left, Fig. 1. Along the sides of the member 1 are disposedupstanding members 2 to form a channel, to prevent the mixed materialsfrom falling 01T the side edges 1. Pivoted at 3 to suitable supports 4are the links 5 pivoted at their lower ends at 6 to the table orvibratory member 1, as by location of the pivots on or in suitablerelation to the elements 2. This structure permits oscillation orvibratory movements of the member 1 when actuated backwardly orforwardly bythe connecting rod or pitman 7, pivoted to the member 1 at8, and at its other end actuated by any suitable means as by a crankupon a shaft driven by an electric or other suitable motor. For thepivotal supporting structure and for the vibrating structure justdescribed may be utilized any other suitable and equivalent structure,the general purpose being to vibrate the primary surface 1 at suitablefrequency, such as heretofore commonly utilized, the direction ofvibration being generally in the direction of the longitudinal extent ofthe surface 1, though it will be understood that the vibratory force maybe applied in any other suitable 01 equivalent direction.

Distributed substantially uniformly throughout the member 1, within thatpart of the length thereof within which the separation is eifected,

are openings or apertures 9 of circular or any other suitable shape andof suitable dimensions. In the example illustrated these apertures arerectangular, and are preferably staggered as indicated in Fig. 5.

On shafts or pivot rods 10, supported by or in xed relation with respectto the member 1 and extending transversely thereof, are pivoted themembers 11, one for each of the openings 9, in such position withrespect thereto as to substantially close them, as hereinafterdescribed. The upper surfaces of these members or gates 11, normallymore steeply inclined than the membervl, are secondary surfaces,partaking of vibration with the member 1, and periodically actuated fromtheir normally open position indicated in Fig. 2 to a position forclosing the apertures or openings 9.

Extending transversely of the screen, table or member 1, adjacent eachtransverse row of openings 9 and members 11, is a shaft or bar 12, whichmay be square in cross section as indicated, with bearings at itsopposite ends in the bearing members 13 carried by or movable with themember 1. Along the member 12, and secured thereto, are distributedangle irons 14, or equivalent, Figs. 2 and 4, whose parts or lugs 15 areadapted to engage the under sides of the members 11 to actuate them upontheir pivots 10.

Secured upon each of the members 12 is a crank or lever arm 16. At theirlower ends the levers 16 are pivoted at 17 to the member or bar 18extending longitudinally of and generally parallel to the vibratorymember 1. v

Secured at its one end at 19 to the member 1 is a spring 20 undertension, secured at its other end to one of the pivots 17 or to a pincarried by the bar 18.

Secured to one of the bars or members 12, as indicated in Fig. 2, is anarm 21 through which is threaded the bolt 22, or equivalent, locked insuitably adjusted position by the nut 23 and adapted to abut against themember l or any suitable part carried thereby. Adjustment of the member22 serves to adjust or determine the opening between the left edges 11a,Fig. 2, of the secondary table or screen members 11, and the left edges9a of the associated openings or apertures 9. This adjustment determinesthe opening at the points aforesaid and through which the slate orseparated material passes off of the members 11.

The operation is as follows:

The mixture of pieces to be separated as of coal and slate previouslygraded as to size in any known manner, as by a grading screen, isdelivered to the right or upper end of the table or screen 1, Fig. 1,which is continually vibrated at suitable frequency and through suitableamplitude by the member '7 or equivalent. The mass so vibrated passesdownwardlyrover the primary surface, the upper surface of the member ortable 1, the coal for example passing over or across the apertures 9,becoming more and more puried of slate as the left or lower end of themember 1 is approached and the separated coal being eventuallydischarged from the lower left end of the member 1 to any suitablereceptacle or destination. The slate of the mixture having diierentweight or specific gravity from that of coal and whose pieces have adiiierent character istic shape from that of coal tends more readily topass through the openings 9 onto the secondary vibratory surfaces of themembers .11, in-` clined more steeply than the table l or the prmarysurface thereof. The pieces of slate pass from the right toward the leftof the secondary surfaces-and pass off the left edges 11a of the members11, Fig. 2, through the space or elongated slot between those edges andthe left edges 9a of the apertures 9 to a suitable receptacle 0rdestination. In Fig. 1 there is shown a hopper 24 into which the slateis delivered and from which it passes through a chute 25 to slate pileor other destination.

The normal position of the secondary surfaces, which are the uppersurfaces of the members 11, with respect to the primary surface of themember 1, is that indicated in Figs. l and 2. The secondary surfaces aremore steeply inclined, with respect to the horizontal, than the primarysurface of the member 1, and during these relative positions of members11 and V1 they are vibrated in unison by the member 7, or equivalent.

During suchV operation there is a tendency of the slate or othermaterial to accumulate upon the members 11, and particularly in thespace between the edges `11a and 9a of members 11 and 9 respectively. Toprevent this accumulation and to keepthe apertures and openings clear,the members 11 are periodically moved from their normal positions intoposition in which their secondary surfaces come substantially intoregister with the primary surface of the member 1. In fact, the membersl1 are periodically brought to position to close the openings '9 in themember 1 with return to their normal positions. This action serves tokeep the passages for the slate or other impurities free at all times.

This movement of the secondary surfaces with respect to the primary, orthe movement of the members 11 substantially to close the openings 9,may be effected by any structure of which that hereinbefore describedinvolving the members 12, 16 and 18, is of a suitable type.

al Cali,

Before the completion oa vibratory movement .of the member land attachedparts towards the leftFigs., 1 and.2,.the.bar or rod lengages a suitablestop or abutment 26. The table 1 and attachedy parts continue theirmovement to the left, thereby causing. relative movement of the bar 18towardthe rightwith respect to the table 1, moving the links or crankarms 16 in counter-clockwise direction, and causing the members 15,carried by theV square bars or shafts 12, to push upwardly on the undersides of the members 11, which. normally rest upon the. members 15,causing the members 11 to. rotate in clockwise direction about theirpivots 10 to position to substantially close the openings 9, clearingout all accumulation of slate or other undesired materials. During thisaperture closing movement of the members 11 the tenson of the spring'20has beenincreased. During t-he return. stroke of the member 1, towardthe right, as soon as the member 18 leaves the abutment 26 the spring 20contracts, moving` the crank arms 16 in clockwise direction, bringingthe abutments 15 and members 11 to normal positions.

While a single spring 20l serves for actuating andV controlling all themembers 11, and while a single adjustable abutment 22 serves foradjusting or determining the normal positions of theV members 11, itwill be understood that a greater number of springs 20 and abutments 22may be used, if and when desirable. But since the several crank arms 16and shafts 12 are interconnected by the bar 18, an adjustment of any oneof them serves to adjust all the members 11, and a single spring` 20will also serve for control and return of all of the secondary screensor gate members 1l.

While in Fig. 5 there is illustrated a series of apertures 9 in atransverse row, it will be` understood that av single aperture 9, and asingle gate member 11, as indicated in Fig. 6, may be utilized extendingsubstantially the entire distance across the table or screen 1. It willfurther be understood that a series of these long transverse apertures 9and members 11 will be provided longitudinally of the table or primaryscreen l. The several long transverse members or gates 11 are correlatedand operated as described in connection with Figs. 2 and 7.

In Figs. 7 and 8 there is illustrated a modification of structure forperiodically moving the secondary screen members 11 with respect to theprimary screen member 1. In this instance the members 11 move in fixedangular position with respect to the crank arms or levers 16 securedupon the cross shafts 12. Again the' several mem.- bers 16 throughoutthe length of the member 1 are connected together by pivoting at 17 tothe bar 18. Again the adjustment of normal positions of all the members11 is procured by the adjustable abutment 22 threaded through the arm 21on one of the members 16, and abutting against the plate 1.

Secured to the left end of the bar 18 is a flexible wire rope 27 orequivalent connected to the rod 28 upon which is threaded the nut 29 andlock nut 30, forming an abutment for the plate- 31 adapted to abutagainst the right hand face of the stop member 26a through which the rod28 extends and on Whose left end is threaded a nut 32 with lock nut 33forming an abutment for the plate 34 between which and the abutmentmember 26a is compressed the spring 20a.

In this modification the ilo-W of mixture of coal and slate or othermaterials is again from right toleft along the member 1, which again ispreferably inclined as indicated in Fig. 1. The spring 20apulls towardthe Vleft upon. rope 27 and rod 28,.whose movement to the left islimited by the abutment 26a when engaged by the' plate 31 backed by thenut 29 uponthe rod 28.

In thisvmodication the secondary screen members or gates 11 are actuatedto close the apertures 9: inthe mainscreen 1 during the latter portionof. the stroke of member l toward the right. Assuming the full stroke ofthe member l, as vibrated by the pitman 7 Vor equivalent, as indicatedin Fig. 1, to be 4 inches, the gate members 11 remain in their normalposition for say three quarters of such stroke or movement, and aremoved-to aperture-closing position during the last inch or quarter ofthe stroke in the forward direction toward the right, in Fig. 7.Assuming the plate 1, Fig. 7, to have completed all but about one inchof its forward stroke toward the right, upon further movement of themember 1 toward the right to complete its stroke in that direction, itwill move toward the right with respect to the bar 18,.causing themembers 11 to move in clockwise direction With their shafts 12, reachingaperture-closing position at the end of the stroke of the member 1 withthe upper surface of each member 1l substantially flush or in registerwith the upper surface of the member l. On the return or backward stroketoward the left, when the member 1 has traveled the same distance, forexample one inch, the members 11 will return to their normal position,indicated in Fig. 7, and remain therein throughout the completion of thebackward stroke and during the longer. portion of the immediatelysucceeding forward stroke to- Ward the right.

Spring 20d, under compression, exerts a force suflicient to operate orcontrol the bar 18 under usual and normal conditions, but will furthercompress and allow full forward movement to the right of the screen 1should a piece of iron or like infrangible material become lodgedbetween a member 11 and the screen 1.

Of all the structures above described, the same action and mode ofoperation are characteristic. Principally because coal is more nearlycubical than slate, which is generally in flat or thin and extendedpieces, the slate passes through the openings 9 on to and along the gatemembers or secondary screens 11, while the coal passes on becausegenerally having no dimension which will permit it to enter into or passthrough the space between the edges 9a and 11d of members 1 and 11respectively.

It is also preferably characteristic of all the structures describedthat the secondary screens or gate members 1l are normally open for themajor portion of the complete forward and return vibration oroscillation of the screen 1, but during any suitable, preferablyv short,portion of the time required for complete forward and return movement ofthe screen 1, each member l1 has imparted thereto the Iaforesaidaperture-closing movement with subsequent return to normal position.

In Fig. 9 is shown a coal grading and cleaningv system. A mixture ofcoal and slate of varying sizes falls from the chute 40 on to a gradingscreen 41 supported by and vibrating with the trough 42. The smallestsizes of coal and slate pass through the apertures of the screen andslide along the bottom. of the trough into discharge slate rejected byscreen 41 slide off plate 44 onto a second grading screenv 45 carried byand vibrating with the trough 46.

The next larger grade of coal and slate pass through the apertures ofthe grading screen45 and travel along the bottom of the trough 46 to thedischarge hopper 47.

The stream of coal and slate from which the two smaller sizes of coalhave been removed, continues along the plate 43, passing onto anothergrading screen 49 which selects the next larger size of coal. As most orthe slate has been removed with the smaller coal sizes, the coal passedby the screen 49 is discharged from the chute 5o to any suitabledestination, as to a car, bin, or as indicated, to a conveyor belt 51for transporting it to a desired destination. Preferably as shown, thecoal in travelling to the chute 50 passes over a screen 52 whose mesh issmaller than that of screen 49, to rescreen the coal, any coal ofsmaller size, not removed by screens 4l or 45, dropping into thecollecting chute of chamber 53, which as indicated, may discharge to aconveyor belt 54.

The largest coal of the original mixture passes beyond screen 49 alongplate 55, 'nally discharging at the end of the trough 46 to any suitablereceptacle, or destination, or as indicated, to a conveyor belt 56 whichtransports it to any suitable point.

Either, or both, of the side streams of graded coal and slate which aredivided from the main stream of coal and slate by the grading screens 41and 45, may pass over a cleaning apparatus or system of the typegenerally shown in Figs. l to 8. Specifically, as shown, the coal andslate passing through the grading screen 45 discharges from chute 47onto a vibrating surface 1, having apertures with which cooperate thesecondary surfaces 11 for removing slate. The graded coal travels alongthe surface 1, discharging into any suitable receptacle as a chute 57.The slate which passes through the openings in plate 1 discharges toanother suitable point, `for example, chute 58.

Preferably as indicated, the slate and any smaller size coal which maypass through the plate falls upon a screen 59, whose openings aresmaller than those ci grading screen 45. The smaller size coal orrescreen is discharged by the hopper 60, as to the conveyor belt 54.

Similarly, the coal and slate graded by screen 4l may be discharged ontoa similar vibrating plate l, and the slate separated from the coal bythe selective action of cleaning apparatus similar to that previouslydescribed.

If the coal and slate has already been graded, it may be dischargeddirectly to the proper cleaning plate Without passing over the gradingscreens, To that end, there are provided openings 61 and 62 in thedischarge hoppers 43 and 47 below screens 41 and 45 respectively fordirect transfer of graded coal and slate to the desired cleaning device.i

With the system shown in Fig. 9, the grading and cleaning of the coal isa vcontinuous process, that is, the various sizes of coal and slate arenot rst segregated as batches of the same grade, with subsequentoperation upon each batch to separate the slate from coal of the samegrade size. With my system there is avoided accumulation of batches ofuncleaned, graded coal, and need for transportation of the accumulationfrom the grading point or points to one or more cleaning stations.

In the system of Fig. 9, it shall be understood,

that the cleaning plate 1 may be vibrated by the same motive means thatvibrates the grading screens, or they may be vibrated from a differentsource.

In Figs. 10 and 11 is shown another type of combined grading andcleaning system. The stream of coal and slate of various sizes passes insuccession over the grading screens 63, 64, and 65, the openings of thescreens being the greater the further the screens are downstream. Thatthe lirst plate, plate 63, has the smallest holes and Veach of thesucceeding screens has holes, larger than those of the preceding screen.Accordingly, the smallest size coal and slate falls through the screen63, the next larger size coal and slate drops through grading screens64, and so on. The largest size coal and whatever slate may remain,falls off the last grading screen upon a cleaning plate 1, of the typepreviously described, which removes the slate, permitting the coal topass on to any suitable destination.

The coal and slate passing through each of the grading screens 63, 64and 65, falls upon a cleaning plate l, which is distinct and separatefrom the others. The mixture of coal and slate falling through thescreen 63 ior example, is cleaned of slate by the first plate 1, thecoal passing out of the discharge duct 66.

Similarly, the stream of coal and slate passed by the grading screen 64falls upon the second plate 1, through which the slate falls, the gradedcoal passing out through a suitable discharge conduit 67. And in likemanner the next higher grade size of coal and slate is cleaned ofV slateand the coal passed to a suitable destination as through a dischargepipe 68. The partitions 69, 70 and 71 which extend across the vibratingtrough, 71, divide it into several chambers each receiving a particulargrade coal, as selected by the screen forming the top of the chamber.The bottom of each chamber is formed by a cleaning plate 1 which removesthe slate from coal oi the same slze.

The actuating bars 18 for the members 1l of the several cleaning platesare, or may be, mechanically coupled, so that all the members 11 areactuated in unison. In this modication, as in that oi Fig. 9, it may bedesirable to adjust the normal openings afforded by the plates l todierent settings from the different cleaning plates. That is, the normalopenings of the plates further downstream will in general, be greaterthan those in the next cleaning plate 11p-stream.

Another grading and cleaning system is illustrated in Figs.- 12 to 14.Referring particularly to Fig. 12, the stream of coal and slate ofvarious sizes discharges from a chute 72 into the grading and cleaningapparatus v75. The smallest size coal falls through the screen 73 to thebottom of the apparatus 75, discharging at 74 to any suitabledestination. The remaining coal and slate passes over the grading screen76 which passes all of the coal. and slate except the larger sizes. Thecoal which does not pass through or is rejected by the screen passesdownwardly along the solid plate 77, the largest size coal passing overthe screen 7S and discharging from the lower or right-hand end of theapparatus as viewed in Fig. 12.

The next largest coal, passes through the screen 78 and is dischargedJfrom the trough 79 to a suitable receptacle or destination.

Neither of the two largest sizes of coal is cleaned of slate by thesystem shown. A large percentage of the slate is removed by the rstgrading screen 76 and the percentage of coal in the larger grades isusually such that in practice it is not separated. It is to beunderstood, however, that, when desirable slate may be removed from thelarger sizes, and preferably by apparatus generally similar to thatshown in Figs. l to 8.

Beneath the grading screen 76 are disposed the several grading screens80, 8l and 82 of progressively smaller mesh. The coal and slate retainedby screen 80 pass onto a cleaning plate 83 generally similar to thatshown and described in Figs. 1 to 8. Coal of the grade passed by screen76 and rejected by screen 89 `passes along the cleaning plate 83discharging at the lower end into a chute extending transversely of thegrading and cleaning apparatus 75. Slate of the same grade passesthrough the openings in plate 83 onto a screen 85, the slate passingover the screen, which as most clearly shown in Fig. 13 forms a V-shapedtrough, and discharging into a pipe or duct 86 extending substantiallyvertically and centrally of the apparatus 75.

Any small coal or slate upon the screen drops through onto the cleaningplate 87 directly below it, which plate 87 also separates slate fromcoal of the size passed by screen 80 and rejected by screen 81. Coal ofthis lower grade size travels along the cleaning plate to any suitabledestination, for example, as shown, to the duct 84. The slate removed bythe selective action of the openings defined by the members 11 and plate87 falls upon a screen 88, substantially V-shaped, as shown in Fig. 13,which discharges into duct 86.

Any small coal or slate upon screen 88 drops through it upon thecleaning plate 89, which receives the coal and slate passed by screen 81and rejected by screen 82. The slate is removed, by action of plate 89,falling upon the screen 90 which discharges into the refuse duct 86. Asindicated the coal passing through the screens 82, 73, and 90 may becombined in a single stream discharging through the opening 74.

Particularly with the system shown in Fig. 12, the percentage of slatein any of the various grades of coal is very low and many times lessthan has heretofore been possible and with much less expensiveequipment. Further, the percentage of coal in the slate refuse isnegligible, so that the method obtains both high purity of coal, withinsubstantial loss. v

The operating bars 18, for the plates l1 of the several plates S3, 87and 89, may be individually operated, or may be mechanically coupledfor.

operation in unison. As indicated most'clearly in Fig. 12, the entireapparatus 75 may be suspended as a unit for vibration by any suitablemeans. The apparatus is preferably suspended, as generally illustrated,by the pivoted arms 91, 92. The entire apparatus may be oscillated byany suitable driving mechanism, and adjacent one extreme of its arcuatemovement the operating bars 18 may engage common, or individual,abutments for effecting proper actuation of the members 11 to preventclogging as previously described. Particularly in view of the fulldescription of Figs. 1 and 8, a more detailed explanation of theoperation of plates 83, 87 and 89 is not necessary. It will beunderstood that it may be desirable in practice to adjust to differentextents the members 11 of the different plates 83, 87 and 89. That is,each of the different cleaning plates may be set by an adjusting screw22 (shown most clearly in Fig. 2), to determine the normal openingbetween the members 11 and the edges 9a of the openings 9, correct forthe particular selection to be effected by that particular plate.

To increase the flexibility of the apparatus, for use with coal whichhas been previously graded, or partly graded, as by exclusion of largersizes, openings 93, 94 and 95 are provided above screens 80, 81 and 82as shown in Fig. 12, to permit af' graded mixture to pass directly tothe proper point in the system for cleaning, and in some instances, forfurther grading and cleaning.

For brevity, in the appended claims the terms coal and slate areemployed in a generic sense to include those materials, and any othermaterials so differing in shape or characteristics that the method andapparatus of the character hereing described is suitable for eiectingtheir separation; and it shall be understood that the term slate withrelation to coal specifically includes other impurities or materials,such as shale, bone and the like.

V/hat I claim is:

1. Apparatus for operating upon a mixture of coal and slate previouslygraded as to size to separate coal from slate comprising an aperturedprimary surface downwardly inclined in the direction or" flow of themixture and devoid of obstructions to free ow of the mixture, means foreffecting reciprocation of said plate longitudinally of said flow, andsecondary surfaces disposed beneath and adjacent the apertures of saidplate and downwardly inclined with respect thereto in the direction offlow, selectively to pass the slate.

2. Apparatus for operating upon a mixture of coal and slate previouslygraded as to size to separate coal from slate comprising a platedownwardly inclined in the direction of flow of the mixture, free ofobstructions to the free iiow of the mixture and having a plurality ofapertures extending substantially across the plate transversely of saidflow, means for effecting reciprocation of said plate longitudinally ofsaid flow, and secondary surfaces disposed beneath and adjacent saidapertures and downwardly inclined from the upper edges thereof,selectively to pass the slate.

3. Apparatus for operating upon a mixture of coal and slate previouslygraded as to size to separate coal from slate comprising an aperturedplate downwardly inclined in the direction of flow of the mixture andfree of obstructions to the free flow of the mixture, means foreffecting reciprocation of said plate longitudinally of said iiow,secondary surfaces disposed beneath and adjacent the apertures of saidplate and downwardly inclined with respect thereto in the direction offlow, selectively to pass the slate, and means for swinging saidsecondary surfaces substantiallyinto the plane of said plate at the endof each stroke.

4. Apparatus for operating upon a mixture of coal and slate previouslygraded as to size to separate coal from slate comprising a platedownwardly inclined in the direction of flow of the mixture, free ofobstructions to the free flow of the mixture and having a plurality ofrectangular apertures extending substantially across the platetransversely of said flow, means for effecting reciprocation of saidplate longitudinally of said flow, secondary surfaces disposed beneathand adjacent said apertures and downwardly inclined from the upper edgesthereof, selectively to pass the slate, and means for swinging saidsecondary surfaces substantially into the plane of said plate at the endof each stroke.

WINFIELD W. STEVENSON, JR.

CERTIFICATE 0F CORRECTION.

Patent No. 1,955,032. April 17, 1934.

WINFIELD W. STEVENSON, JR.

it is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 4,line 124, for the numeral "1" read 11; page 5, tine 16, for "a chute"reed the chute 84; and lines 91-92, for "hereing" read herein; and thatthe said Letters Patent should be read with these corrections thereinthat the same may conform to the record of the case in the Patent(lifiee.

Signed and sealed this 19th day of June, A. D. 1934.

Bryan M. Battey (Seal) Acting Commissioner of Patents,

